The Journal of critical illness最新文献

Malpositioning of a central venous catheter can cause potentially life-threatening complications. Knowledge of thoracic anatomy and close attention to proper insertion technique increase the likelihood of, but do not ensure, proper placement. Selection of a right-sided venous entry site reduces the risk of malpositioning. The return of nonpulsatile, dark-colored blood is a strong, but not infallible, indication of venous placement. Do not assume that venous system valves preclude malpositioning. Use chest films to confirm accurate insertion. When these are equivocal, take simultaneous blood samples from a peripheral artery and the central line; the samples will have markedly different blood gas levels if the catheter is in a vein.

Major problems facing cardiac transplant recipients include rejection, infection, and transplant coronary artery disease. Commonly used antirejection drugs are high-dose corticosteroids and cytolytic agents. Bacterial infections, such as those caused by staphylococci, occur early in the postoperative period, while opportunistic infections, including viral, fungal, and parasitic diseases, occur several weeks after transplant surgery. Coronary angiography is used to detect transplant coronary artery disease, the only definitive treatment for which is retransplantation. A number of promising new immunosuppressive agents and techniques may prevent some complications and further improve the care cardiac transplant recipients receive.

Chest tube insertion is warranted for drainage of large exudative pleural effusions, empyemas, hemothoraces, or chylothoraces, and for some pneumothoraces or parapneumonic effusions. Chest tubes may also be used to instill sclerosing agents to prevent recurrent malignant effusions or pneumothorax. There are no absolute contraindications to tube thoracostomy; however, if time allows, effort should be made to correct any coexisting hemorrhagic disorders before the procedure is performed. Pleurodesis may be contraindicated in patients who are expected to undergo lung surgery. The incisional method is safest for chest tube insertion and pleurodesis; bear in mind, however, that some patients with pneumothorax may be better treated with small-caliber drainage.

MI is often recognized less promptly in elderly patients than in younger patients; thus, the best opportunity for reperfusion is often missed. If infarction is diagnosed in less than 12 hours and there are no strong contraindications, thrombolytic therapy is appropriate for the elderly. Coronary angioplasty is a suitable alternative if performed promptly, especially because elderly patients are more likely to have contraindications to, or higher mortality from, thrombolysis. Predictors of unfavorable outcome following angioplasty for acute MI in the elderly include multivessel disease, occlusion of the infarcted artery, and cardiogenic shock. CABG surgery (performed during infarction or in the peri-infarct setting) is also an option for those elderly patients who are hemodynamically stable.

Complications limiting the use of percutaneous transluminal coronary angioplasty (PTCA) include abrupt vessel closure and restenosis. Certain coronary lesions, such as chronic total occlusions and diffuse or long stenoses, pose serious technical difficulties. New devices may overcome some of these limitations. For example, atherectomy may prove useful for thrombotic vessels or diffusely diseased vein grafts, and it may lower restenosis rates in larger vessels. Stents are currently used as a bailout measure when acute dissection occurs. Although lasers produce smoother margins than does conventional PTCA and effectively ablate atherosclerotic plaque material, the restenosis rate associated with use of these devices may be similar to that of conventional PTCA.

When a patient requires parenteral fluid or drug administration and venous cannulation cannot be performed, consider less typical routes. Intraosseus infusions are usually more effective in children than adults, but intraosseus cannulation failure may occur in as many as 20% of patients. Intra-arterial infusions are possible if pump pressures are kept high. Hypodermoclysis (infusion into the subcutaneous tissues) can correct moderate dehydration. Administering resuscitative drugs endobronchially is usually safe and effective, although pulmonary function may be somewhat compromised. A number of drugs may be given sublingually, either by injection or topical application. Finally, the corpora cavernosa of the penis may be used for short-term, large-volume fluid administration.

There are a number of therapeutic options for fluid administration in patients who lack usual venous access. Ways to establish this access include limb elevation and wrapping, the application of nitroglycerin ointment to dilate veins, and blood pressure cuff inflation. Ultrasonography can also be used to delineate vascular structures. Cutdown procedures are the oldest, most direct method to reach uncommon venous sites, such as the inferior epigastric, intercostal, iliac, and lateral thoracic veins. Today, cutdown procedures are regarded as the method of last resort, and they should be performed in operating suites or similar settings. Possible complications include inadvertent arterial puncture and hemorrhage.

The use of percutaneous transluminal coronary angioplasty has expanded tremendously over the past decade. Because equipment has improved and physicians' experience has increased, the procedure is often appropriate for patients with complex lesions or difficult coronary anatomies. Currently, stenoses are successfully opened in more than 90% of patients. Angioplasty is an alternative to medical therapy for patients with one- or two-vessel disease; in some patients with multivessel disease, it is an alternative to coronary artery bypass graft surgery. Among elderly patients, those who are poor candidates for bypass surgery, those who have had previous bypass surgery, and those with acute myocardial infarction or cardiogenic shock, coronary angioplasty may be particularly useful.